The present invention relates generally to a reinforced structural assembly for use in strengthening, stiffening or stabilizing different portions of an automotive vehicle. More particularly, the present invention relates to a reinforced structural assembly for placement in a cavity of an automotive vehicle wherein the assembly includes a first structural member generally opposing a second structural member with a layer of expandable material intermediate the members for moving each of the members toward one or more walls defining the cavity of the vehicle.
For many years the transportation industry has been concerned with designing reinforced structural members or assemblies that do not add significantly to the weight of a vehicle. For example, U.S. Pat. Nos. 5,755,486; 4,901,500; and 4,751,249 describe prior art reinforcing devices. Generally, the reinforced structural members have used expandable materials combined with other materials for forming structural members that fit into one or more cavities of an automotive vehicle. Once the structural members are placed in the cavities the expandable materials may be expanded to secure the members in the cavities. Typically, it is desirable to maintain some degree of control over the amount of expansion experienced by the expandable materials since the amount of expansion may at least partially dictate the structural or strength properties exhibited by the materials. However, such control may be difficult since cavities of automotive vehicles tend to vary in size due to factors such as size tolerances of vehicle components and the like.
In addition to variability in size, the shapes of the cavities can cause difficulties in forming structural members that fit properly in the cavities. Moreover, the sizes of openings through which the structural members are inserted to place the structural members in the cavities may be relatively small, which may cause assembly problems for the structural members. Thus, there is a need for a reinforced structural assembly that can be effectively used in cavities that have various shapes, various sizes, variably sized openings or a combination thereof.
The present invention is directed to a structural reinforcement assembly adapted for placement in a cavity of an automotive vehicle and, more particularly, a reinforcement assembly having one or more degrees of adjustability to assist the assembly in forming a reinforcement system with components of an automotive vehicle. Generally speaking, the assembly may utilize technology and processes such as those disclosed in U.S. Pat. Nos. 4,922,596, 4,978,562, 5,124,186, and 5,884,960 and commonly owned, co-pending U.S. application Ser. Nos. 09/502,686 filed Feb. 11, 2000 and 09/524,961 filed Mar. 14, 2000, all of which are expressly incorporated by reference. The assembly generally employs a first and second member, each member including a first surface generally opposing a second surface. The assembly also typically includes reinforcement material intermediate the first and second members. The reinforcement material is preferably configured for contacting the first surfaces of the first and second members during expansion of the reinforcement material such that the second surfaces of the members form a connection with surfaces defining the cavity within an automotive vehicle. Preferably the reinforcement material is an energy absorbing medium, and a heat activated bonding material. In a particular preferred embodiment, the first and second members could be formed of injection molded nylon, injection molded polymer, or molded metal (such as aluminum, magnesium, steel and titanium, an alloy derived from the metals, and even a metallic foam). The reinforcement material may be a foamable or expandable material, which could comprise an epoxy-based resin, such as L5204, L5206, L5207, L5208 or L5209 structural foam commercially available from L and L Products of Romeo, Mich. Additional foamable or expandable materials that could be utilized in the present invention include other materials which are suitable as bonding mediums and which may be heat activated foams which activate and expand to fill a desired cavity or occupy a desired space or function when exposed to temperatures typically encountered in automotive e-coat and other paint operations. In addition, it is contemplated that the first and second members could comprise a nylon or other polymeric material as set forth in commonly owned U.S. Pat. No. 6,103,341, expressly incorporated by reference herein.
Though other heat-activated materials are possible, a preferred heat activated material is an expandable or flowable polymeric formulation, and preferably one that is activated to foam, flow or otherwise change states when exposed to the heating operation of a typical automotive assembly painting operation. For example, without limitation, in one embodiment, the polymeric foam is based on ethylene copolymer or terpolymer that may possess an alpha-olefin. As a copolymer or terpolymer, the polymer is composed of two or three different monomers, i.e., small molecules with high chemical reactivity that are capable of linking up with similar molecules. Examples of particularly preferred polymers include ethylene vinyl acetate, EPDM, or a mixture thereof. Without limitation, other examples of preferred foam formulation that are commercially available include polymer-based material commercially available from LandL Products, inc. of Romeo, Mich., under the designations as L-2105, L-2100, L-7005 or L-2018, L-7101, L-7102, L2411, L-2412, L-4141, etc. and may comprise either open or closed cell polymeric base material.
A number of other suitable materials are known in the art and may also be used for vibration reduction. One such foam preferably includes a polymeric base material, such as an ethylene-based polymer which, when compounded with appropriate ingredients (typically a blowing and curing agent), expands and cures in a reliable and predicable manner upon the application of heat or the occurrence of a particular ambient condition. From a chemical standpoint for a thermally activated material, the vibration reducing foam is usually initially processed as a flowable thermoplastic material before curing. It will cross-link upon curing, which makes the material resistant of further flow or change of final shape.
It is contemplated that the reinforcement material could be delivered and placed into contact with the assembly members, through a variety of delivery systems which include, but are not limited to, a mechanical snap fit assembly, extrusion techniques commonly known in the art as well as a mini-applicator technique as in accordance with the teachings of commonly owned U.S. Pat. No. 5,358,397 (xe2x80x9cApparatus For Extruding Flowable Materialsxe2x80x9d), hereby expressly incorporated by reference. In this non-limiting embodiment, the material or medium is at least partially coated with an active polymer having damping characteristics or other heat activated polymer, (e.g., a formable hot melt adhesive based polymer or an expandable structural foam, examples of which include olefinic polymers, vinyl polymers, thermoplastic rubber-containing polymers, epoxies, urethanes or the like) wherein the foamable or expandable material can be snap-fit onto the chosen surface or substrate; placed into beads or pellets for placement along the chosen substrate or member by means of extrusion; placed along the substrate through the use of baffle technology; a die-cast application according to teachings that are well known in the art; pumpable application systems which could include the use of a baffle and bladder system; and sprayable applications.
In one embodiment the assembly including the first and second members along with a suitable amount of reinforcement material intermediate the members is placed in a cavity defined within an automotive vehicle, between components such as a panel and a battery support tray or other area or substrate found in an automotive vehicle which could benefit from the structural reinforcement, vibrational reduction, noise reduction characteristics or a combination thereof found in the present invention. Once in place, the reinforcement material of the assembly may be activated to expand such that the first and second members are moved away from each other to contact the components defining the cavity.